Watch What Happens: Live: The Little Late-Night Show That Could

Instead of a monologue, there's a Mazel (and Jackhole) of the Week. Instead of coffee or water, the guests get cocktails from the on-set bar. And rather than musical performances from chart-toppers and Grammy winners, the tunes come courtesy of acts such as Real Housewives stars Kim Zolciak and Countess LuAnn de Lesseps.

Now in its third season, Watch What Happens: Live is one of late-night's surprise hits. So far this season, the Bravo program has hosted Tina Fey and Ralph Fiennes (in character as Harry Potter baddie Voldemort no less). In July, the show scored its biggest audience with 2.4 million viewers and Season 3 has averaged 1.3 million viewers, jumping 62 percent from last season and proving a formidable competitor against 11 p.m. stalwarts such as Chelsea Lately and The Daily Show.

"The vibe of it is very clubby, but it's a club that everybody's invited to," Cohen says. "Everyone else goes really big in late-night and we kind of localize it and just host a small little cocktail party at 11 p.m. and it's having great results."

Following the show's smooth expansion from one night to two last month, Watch What Happens: Live will air five straight nights this week starting Monday. Guests include Anderson Cooper, Diane von Furstenberg, Denise Richards and Amy Sedaris. "It's an opportunity for us to talk fashion and food and just have fun more nights a week," Cohen says. "Keep that clubhouse going."

Based on Cohen's online series of the same name, Watch What Happens: Live started in July 2009 at midnight with little fanfare. The show was only supposed to last three months, but the show clicked with Bravo viewers.

"It started small and decided to be like the little engine that could," co-executive producer Deirdre Connolly says. "There was no expectation; nobody really knew what it was going to turn into. It was kind of an organic experience and the success came because the pressure wasn't really there."

In the beginning, the show primarily served as a way for Cohen to interact with viewers about the latest Housewives blow-up or Top Chef eliminee, and for Bravolebrities to sit back, play games like Naked Wasted Charades.

Although being the only live show in late-night would be a stressful undertaking for many, Cohen embraced it, tapping into not only his experience hosting so many Bravo showreunions but also his previous gig as a senior producer on CBS' The Early Show.

"I think that Andy sets a tone of having a lot of fun with the crew and having nice relationships with everyone and joking around," Connolly says. "You really feel like you're in Andy's living room hanging out with him. He's just a natural at what he does."

With time, Watch What Happens: Live began catching on with viewers, as well as celebrities. Before they appeared on the show, Neil Patrick Harris, Ellen Barkin and Cooper all sat in the small live studio audience of fewer than 20 people in Tribeca. "Our audience is basically next to our camera guys, who are right next to our guests so it's like this tiny little room where everyone is mingling and our audience is essentially apart of the set," Connolly says of the set. "Everything else is like, 'OK you need to clap now. Here's your applause.' None of that is going on. It's very genuine."

The on-screen talent caught up with the talent sitting behind the camera in Season 2, with appearances from Liam Neeson and Jerry Seinfeld.

"There's no pre-interview on our show. The people come, I do my research, the viewers ask their questions and we just go with it live," Cohen says. "I think that spontaneity is really key and that's the bulk of the show."

Adds Connolly: "Because it's relaxed, people tend not to just tell their soundbite stories and promote their stuff. They let loose a little bit. It just feels like a conversation that you're eavesdropping on."

For example, when Seinfeld was on in May, he spent more time ribbing Cohen than chatting up The Marriage Ref. When Fey stopped by in October, instead of discussing 30 Rock or Megamind, she spent a most of the 30 minutes using Mean Girls source material to analyze The Real Housewives of New York City. "That was just huge that she came," Connolly says. "[That] was kind of a moment where I was in awe of where we've come in the last year and a half."

No matter what talent the show is able to nab, both Cohen and Connolly stress the show's fans will always important. Viewers are welcome to tweet, Facebook or call to ask a question of the guests or the host. The interactive element has even produced a Bravolebrity of its own — frequent caller and 13-year-old Real Housewives expert Ben Weiner.

"Without people weighing in, our show wouldn't be what it is at all," Connolly says. "Andy really listens to what people say. It's important to us just getting feedback and knowing that people are as much apart of the show as the guests in our studio."

As the show continues to experiment — after this week's five live shows, Watch What Happens will also broadcast live on New Year's Eve — there are hopes to invite even more interaction with viewers. But don't expect the program to outgrow its cramped quarters anytime soon.

Says Cohen: "I think it's really important that it's live, that it's spontaneous and fun, and I like the small scale of it."